[RFA] comment cleanup in exceptions.[ch]

[dje at google dot com (Doug Evans)]

Hi.

While looking into using catch_errors/exceptions for something
I ran into some confusing/outdated comments.
I don't know all the details of catch_exceptions to be comfortable
that the result still doesn't have problems, but it is better
than before.

The high order bit here is that I copied the lead paragraph for
catch_exceptions from exceptions.h to exceptions.c and added
a reference back to exceptions.h (it seemed like some text more
than just "see exceptions.h" was useful in exceptions.c),
plus I moved the usage text of MASK to exceptions.h.

I also removed an outdated FIXME regarding utils.c/top.c.
Given that exceptions.[ch] exists I think this FIXME can go.

Ok to check in?

2008-12-04  Doug Evans  <dje@google.com>

	* exceptions.h: Clean up some comments on catch_exceptions usage.
	* exceptions.c: Ditto.  Plus mark catch_errors as superseded by
	catch_exceptions.

Index: exceptions.c
===================================================================
RCS file: /cvs/src/src/gdb/exceptions.c,v
retrieving revision 1.30
diff -u -p -r1.30 exceptions.c
--- exceptions.c	8 Sep 2008 21:46:21 -0000	1.30
+++ exceptions.c	4 Dec 2008 21:12:21 -0000
@@ -417,25 +417,21 @@ throw_error (enum errors error, const ch
   va_end (args);
 }
 
-/* Call FUNC() with args FUNC_UIOUT and FUNC_ARGS, catching any
-   errors.  Set FUNC_CAUGHT to an ``enum return_reason'' if the
-   function is aborted (using throw_exception() or zero if the
-   function returns normally.  Set FUNC_VAL to the value returned by
-   the function or 0 if the function was aborted.
+/* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
+   handler.  If an exception (enum return_reason) is thrown using
+   throw_exception() than all cleanups installed since
+   catch_exceptions() was entered are invoked, the (-ve) exception
+   value is then returned by catch_exceptions.  If FUNC() returns
+   normally (with a positive or zero return value) then that value is
+   returned by catch_exceptions().  It is an internal_error() for
+   FUNC() to return a negative value.
+
+   See exceptions.h for further usage details.
 
    Must not be called with immediate_quit in effect (bad things might
    happen, say we got a signal in the middle of a memcpy to quit_return).
    This is an OK restriction; with very few exceptions immediate_quit can
-   be replaced by judicious use of QUIT.
-
-   MASK specifies what to catch; it is normally set to
-   RETURN_MASK_ALL, if for no other reason than that the code which
-   calls catch_errors might not be set up to deal with a quit which
-   isn't caught.  But if the code can deal with it, it generally
-   should be RETURN_MASK_ERROR, unless for some reason it is more
-   useful to abort only the portion of the operation inside the
-   catch_errors.  Note that quit should return to the command line
-   fairly quickly, even if some further processing is being done.  */
+   be replaced by judicious use of QUIT.  */
 
 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
    error() et.al. could maintain a set of flags that indicate the the
@@ -445,10 +441,6 @@ throw_error (enum errors error, const ch
    code also randomly used a SET_TOP_LEVEL macro that directly
    initialize the longjmp buffers. */
 
-/* MAYBE: cagney/1999-11-05: Should the catch_errors and cleanups code
-   be consolidated into a single file instead of being distributed
-   between utils.c and top.c? */
-
 int
 catch_exceptions (struct ui_out *uiout,
 		  catch_exceptions_ftype *func,
@@ -505,6 +497,8 @@ catch_exceptions_with_msg (struct ui_out
   return val;
 }
 
+/* This function is superseded by catch_exceptions().  */
+
 int
 catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
 	      return_mask mask)
Index: exceptions.h
===================================================================
RCS file: /cvs/src/src/gdb/exceptions.h,v
retrieving revision 1.22
diff -u -p -r1.22 exceptions.h
--- exceptions.h	1 Jan 2008 22:53:09 -0000	1.22
+++ exceptions.h	4 Dec 2008 21:12:21 -0000
@@ -177,7 +177,7 @@ extern NORETURN void deprecated_throw_re
    throw_exception() than all cleanups installed since
    catch_exceptions() was entered are invoked, the (-ve) exception
    value is then returned by catch_exceptions.  If FUNC() returns
-   normally (with a postive or zero return value) then that value is
+   normally (with a positive or zero return value) then that value is
    returned by catch_exceptions().  It is an internal_error() for
    FUNC() to return a negative value.
 
@@ -191,10 +191,19 @@ extern NORETURN void deprecated_throw_re
    copy of the gdb error message.  This is used when a silent error is 
    issued and the caller wants to manually issue the error message.
 
+   MASK specifies what to catch; it is normally set to
+   RETURN_MASK_ALL, if for no other reason than that the code which
+   calls catch_errors might not be set up to deal with a quit which
+   isn't caught.  But if the code can deal with it, it generally
+   should be RETURN_MASK_ERROR, unless for some reason it is more
+   useful to abort only the portion of the operation inside the
+   catch_errors.  Note that quit should return to the command line
+   fairly quickly, even if some further processing is being done.
+
    FIXME; cagney/2001-08-13: The need to override the global UIOUT
    builder variable should just go away.
 
-   This function superseeds catch_errors().
+   This function supersedes catch_errors().
 
    This function uses SETJMP() and LONGJUMP().  */
 
@@ -225,7 +234,7 @@ extern struct gdb_exception catch_except
    indication of the exact exception that it caught - quit_flag might
    help.
 
-   This function is superseeded by catch_exceptions().  */
+   This function is superseded by catch_exceptions().  */
 
 typedef int (catch_errors_ftype) (void *);
 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);